Self propelled combines and forage harvesters usually include means for either cutting stalk crops close to the ground or snapping the ears off standing corn. Basic working components of the harvester are the thresher or crop processor and a header unit mounted transversely at the front thereof. The header unit contains the cutter bar or snapping rolls, the means for centrally grouping the crop and an elevator assembly for delivering the plants or selected portions thereof to the thresher or processor.
Arrayed across the front of the header unit are a number of row dividers. For example, if the header is designed for harvesting four rows of corn simultaneously, there would be 5 row dividers spaced at equal intervals across the front of the header. The row dividers serve to pick up bent stalks, lifting and steering them into the harvesting machinery.
Many different harvesters have been built for gathering row crops. Most of them require close attention by the machine operator, who must not only steer down the rows but also manually adjust the height of the header above the ever changing terrain contours. As harvesting machines were made bigger so they could process more rows simultaneously and at the same time move through the field at a faster pace, the burden on the machine operator became increasingly difficult when trying to handle everything by manual control.
Applicant found that the harvesting job could be accomplished easier and more efficiently if automatic header height control were incorporated. To do this, sensors were incorporated which make electrical contact to control solenoid valves which direct a hydraulic system to automatically change header height to maintain it within a desired float range above ground.